Thread hardening part 3. Now lldb_private::Thread objects have std::weak_ptr
objects for the backlink to the lldb_private::Process. The issues we were
running into before was someone was holding onto a shared pointer to a 
lldb_private::Thread for too long, and the lldb_private::Process parent object
would get destroyed and the lldb_private::Thread had a "Process &m_process"
member which would just treat whatever memory that used to be a Process as a
valid Process. This was mostly happening for lldb_private::StackFrame objects
that had a member like "Thread &m_thread". So this completes the internal
strong/weak changes.

Documented the ExecutionContext and ExecutionContextRef classes so that our
LLDB developers can understand when and where to use ExecutionContext and 
ExecutionContextRef objects.



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@151009 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/source/Commands/CommandObjectBreakpointCommand.cpp b/source/Commands/CommandObjectBreakpointCommand.cpp
index 7283e6d..a7e98ea 100644
--- a/source/Commands/CommandObjectBreakpointCommand.cpp
+++ b/source/Commands/CommandObjectBreakpointCommand.cpp
@@ -799,7 +799,8 @@
     
     if (commands.GetSize() > 0)
     {
-        Target *target = context->exe_ctx.GetTargetPtr();
+        ExecutionContext exe_ctx (context->exe_ctx_ref);
+        Target *target = exe_ctx.GetTargetPtr();
         if (target)
         {
             CommandReturnObject result;
@@ -817,7 +818,7 @@
             bool print_results    = true;
 
             debugger.GetCommandInterpreter().HandleCommands (commands, 
-                                                             &(context->exe_ctx),
+                                                             &exe_ctx,
                                                              stop_on_continue, 
                                                              data->stop_on_error, 
                                                              echo_commands, 
diff --git a/source/Commands/CommandObjectRegister.cpp b/source/Commands/CommandObjectRegister.cpp
index 7b0e0c3..c34e6ee 100644
--- a/source/Commands/CommandObjectRegister.cpp
+++ b/source/Commands/CommandObjectRegister.cpp
@@ -96,17 +96,20 @@
                 bool prefix_with_altname = m_command_options.alternate_name;
                 bool prefix_with_name = !prefix_with_altname;
                 reg_value.Dump(&strm, reg_info, prefix_with_name, prefix_with_altname, m_format_options.GetFormat());
-                if (((reg_info->encoding == eEncodingUint) || (reg_info->encoding == eEncodingSint)) && 
-                    (reg_info->byte_size == reg_ctx->GetThread().GetProcess().GetAddressByteSize()))
+                if ((reg_info->encoding == eEncodingUint) || (reg_info->encoding == eEncodingSint))
                 {
-                    addr_t reg_addr = reg_value.GetAsUInt64(LLDB_INVALID_ADDRESS);
-                    if (reg_addr != LLDB_INVALID_ADDRESS)
+                    Process *process = exe_ctx.GetProcessPtr();
+                    if (process && reg_info->byte_size == process->GetAddressByteSize())
                     {
-                        Address so_reg_addr;
-                        if (exe_ctx.GetTargetRef().GetSectionLoadList().ResolveLoadAddress(reg_addr, so_reg_addr))
+                        addr_t reg_addr = reg_value.GetAsUInt64(LLDB_INVALID_ADDRESS);
+                        if (reg_addr != LLDB_INVALID_ADDRESS)
                         {
-                            strm.PutCString ("  ");
-                            so_reg_addr.Dump(&strm, exe_ctx.GetBestExecutionContextScope(), Address::DumpStyleResolvedDescription);
+                            Address so_reg_addr;
+                            if (exe_ctx.GetTargetRef().GetSectionLoadList().ResolveLoadAddress(reg_addr, so_reg_addr))
+                            {
+                                strm.PutCString ("  ");
+                                so_reg_addr.Dump(&strm, exe_ctx.GetBestExecutionContextScope(), Address::DumpStyleResolvedDescription);
+                            }
                         }
                     }
                 }